1. Field of the Invention
The present invention relates to a linear transmission positioning structure, and more particularly to a linear feedback positioning module for correction of error caused by linear movement.
2. Description of the Prior Art
Linear positioning modules are widely used in laser drilling machines, small milling machines, image inspection equipments, etc. Referring to FIGS. 4-5, a conventional linear positioning module comprises a loading assembly 10, a drive assembly 20 and a movable assembly 30. The loading assembly 10 is a platform 10 with a leading screw 12. The drive assembly 20 is a coupling 21 connected with a motor 22. The drive assembly 20 is fixed at one side of the loading assembly 10, and the motor 22 is connected to the lead screw 12 through the coupling 21. The movable assembly 30 is fitted on the loading assembly 10 and moves along the lead screw 12.
When in use, the motor 22 is driven by a controller, and the controller determines the amount of feed required for the rotation of the motor. When the motor 22 rotates, the coupling 21 is driven, so that the coupling 21 can control the required amount of displacement of the movable assembly 30 along the lead screw 12.
However, the manner in which the motor 22 utilizes the rotation of the coupling 21 to drive the lead screw 12 to rotate axially will cause angle difference to most of gear mates, which will cause an unacceptable tolerance after a long time of use. In addition, if the respective gears are used with the lead screw 12 for long time, back clearance is likely to occur between the gears due to attrition. The occurrence of the back clearance can also cause the accumulated error. Additionally, the lead screw is too long, so the distortion and eccentricity of the lead screw are usually invisible, after a long time of accumulation, they can also cause a very large error. Therefore, such a linear positioning module must be regularly checked by a laser measure, and the checking data will be provided for correcting the linear positioning module, thus wasting time and labor. In addition, when the checking operation is performed, the machine must be shutdown, so the production efficiency is greatly reduced. Moreover, since the product accuracy cannot be ensured due to the error caused by the linear positioning module, the product competitiveness is relatively low.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages.